This invention relates generally to tool and die assemblies, and more particularly to punch retainers for use in a punch and die assembly.
When sheet metal or other types of products are manufactured, it is often necessary that the products include one or more apertures. Typically a die with a punch secured thereto is used to create these apertures in the product to be manufactured. An example of such a punch 1000 is depicted in FIG. 8. Punch 1000 includes a piercing end 1002, which contacts and pierces the product under manufacture. The punch 1000 is secured to a punch retainer 1004, which is in turn secured to a die shoe 1006. Between the punch retainer 1004 and die shoe 1006, a backing plate 1008 is typically secured. As the entire assembly moves downward, punch 1000 contacts the product and pierces it. Punch 1000 can take on a variety of different dimensions depending upon the desired dimensions of the aperture to be created.
Punch retainers 1004 come in a variety of different shapes. As illustrated in FIGS. 9-11, there are three standard types of prior art punch retainers. FIG. 9 depicts a generally triangular shaped punch retainer, which is often referred to as a true retainer. FIG. 10 depicts a square retainer and FIG. 10 depicts an end retainer. Each of the retainers includes a punch aperture 1010 into which a punch 1000 is inserted. As shown in FIGS. 9-11, each of the punch retainers also includes a pair of alignment holes 1012 which receive dowel pins and are used for properly aligning the punch retainer on the die shoe 1006. Each of the punch retainers also includes a pair of fastener holes 1014 through which a fastener, such as a screw or bolt is inserted in order to secure the punch retainer to the die shoe 1006.
The prior art punch retainers depicted in FIGS. 9-11 suffer from the disadvantage that they cannot be closely spaced together. In other words, if the product being manufactured requires a number of closely spaced holes that are to be created by a punch, the punch retainers shown in these figures cannot be used. For example, as shown in FIG. 12, punch aperture 1010 is located a distance A from the front end of the punch retainer. Punch aperture 1010 is also located a distance B from the side of the punch retainer. A pair of punch retainers like the one of FIG. 12 can therefore not be used to create a hole pattern in which the holes are spaced closer than either the distance 2A or 2B. This limitation on the closeness of the holes that can be punched using prior art punch retainers has been difficult to overcome.
In order to create closely spaced together holes in the past, it has been necessary for most machine shops to special order a custom-made punch retainer that will accommodate the desired hole pattern. While some machine shops have the necessary tools to make such a custom-made part, it is beyond the ability of the majority of machine shops. Consequently, those machine shops which have had to order the custom-made part have often had to wait up to a week or more for the part to be created and delivered. The specially ordered part has also typically cost significantly more than the standard punch retainers depicted in FIGS. 9-12. The creation of closely spaced punched holes in the past has therefore undesirably required the expenditure of additional time and money in order for the appropriate parts to be custom-made.
The only other option in the past for accommodating closely spaced hole patterns was to use a retainer with a headed punch. Headed punch retainers, however, do not have ball locks, or other types of locks, with release mechanisms. Headed punch retainers therefore suffer from the disadvantage that the headed punch cannot be removed from the retainer without removing the entire retainer from the die shoe. This makes the sharpening of the punch, or other types of maintenance, extremely labor intensive. The need can therefore be seen for a punch retainer which allows closely spaced hole patterns to be created, and at the same time is both inexpensive and easy to create and easy to maintain.
Accordingly, the present invention provides a punch retainer which is both easy to create and maintain. The punch retainer according to one aspect of the present invention includes a body having a top and bottom face. An aperture is defined in the body for receiving the punch. The aperture extends from the top face to the bottom face of the body. The punch retainer further includes a peripheral surface on the body that is tapered inwardly from the top face to the bottom face of the body.
A punch retainer according to another aspect of the invention includes a body having a top and bottom face. The body includes no fastener holes for receiving a fastener that is used to secure the body to a die shoe. The body further includes an aperture for receiving a punch, along with a lock for selectively retaining the punch in the aperture.
According to still another aspect of the invention, a punch retainer system includes at least one insertable punch retainer having a body that defines an aperture for receiving a punch. The system further includes a retainer block that has at least one recess configured to snugly receive the insertable punch retainer. The retainer block further includes at least one hole for receiving a fastener that is used to secure the retainer block to a die shoe.
In yet another aspect of the invention, a method for securing a punch to a die includes the steps of providing an insertable punch retainer having an aperture for receiving a punch. A retainer block is also provided. A recess is cut in the retainer block such that the recess has a shape that is dimensioned to receive the insertable punch retainer. The insertable punch retainer is then inserted into the recess and the retainer block is fastened to a die shoe.